Rotating pump

ABSTRACT

A rotating pump includes an outer and an inner rotor disposed in a casing with a gap between the casing and the outer rotor. The rotating pump also includes a first and a second sealing member in the casing to define a low-pressure region and a high-pressure region within the gap. Each of the first and second sealing members is made up of a seal functioning portion and an elastically pressing portion. The seal functioning portion includes a resinous member and a deformation-suppressing member. The resinous member contacts the outer rotor and a low-pressure side inner surface of the casing to establish a difference in pressure between the low-pressure region and the high-pressure region. The deformation-suppressing member works to stop the resinous member from deforming undesirably. This minimizes the risk of breakage of the resinous member and enables the rotating pump to discharge the fluid at an increased pressure.

The present application claims the benefit of priority of JapanesePatent Application No. 2014-22442 filed on Feb. 7, 2014, the disclosureof which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1.Technical Field of the Invention

This disclosure relates generally to a rotating pump designed to suckand then discharge fluid, and more particularly to such a rotating pumpwhich is useful for a brake system working to suck and discharge brakefluid to regulate the pressure thereof for controlling the brakingforce.

2. Background Art

Japanese Patent First Publication No. 2002-295376 teaches use of aninternal gear pump, such as a trochoid pump, as a rotating pump for anautomotive brake system. This type of rotating pump is made up of aninner rotor, an outer rotor, and a casing. The inner rotor is equippedwith outer teeth formed on an outer periphery thereof. The outer rotoris equipped with inner teeth formed on an inner periphery thereof. Theouter and inner rotors are mounted in the casing. Specifically, withinthe casing, the teeth of the inner rotor mesh with those of the outerrotor to define a plurality of cavities (i.e., clearances). If a linepassing through the centers of the inner rotor and the outer rotor isdefined as the center line of the pump, the pump has an inlet port(i.e., a suction side) and an outlet port (i.e., a discharge side) whichare diametrically opposed to each other across the center line of thepump.

In operation of the pump, the inner rotor is rotated by a drive shaft,so that the outer rotor is rotated in the same direction as the innerrotor through the meshing of the outer teeth and the inner teeth. Thiscauses the volumes of the cavities to increase and then decreasecontinuously to suck fluid from the inlet port and then discharge itfrom the outlet port every 360° rotation of the outer and inner rotors.

During the operation of the pump, gaps between the outer periphery ofthe outer rotor and the casing are broken down into a low-pressureregion and a high-pressure region. A sealing member is, therefore,disposed on the outer periphery of the outer rotor to hermeticallyisolate the low-pressure and high-pressure regions from each other.Specifically, the casing has two cavities formed on portions of theinner circumference thereof which face the outer circumference of theouter rotor. Sealing mechanisms each made up of a resin member and arubber member are disposed in the cavities, respectively. The rubbermember is placed on the bottom of the cavity of the casing, while theresin member is laid between the rubber member and the outer rotor. Therubber member, thus, presses the resin member into constant abutmentwith the peripheral surface of the outer rotor to hermetically sealbetween the low-pressure region and the high-pressure region.

In recent years, there has been an increasing demand for the pump todischarge brake fluid at high pressure. The above described conventionalsealing mechanisms, however, need to have a large clearance between thecasing and the outer rotor for meeting a pressure requirement because ofdesign limitations in terms of production tolerance of the pump. It is,therefore, impossible for the pump to have the required enduranceagainst the discharge of the brake fluid at high pressure. For instance,the resin member may deform into the clearance between the casing andthe outer rotor, thereby resulting in breakage of the resin member,which leads to a lack of sealing ability of the sealing mechanism.Usually, the resin member is easy to deform, especially, at hightemperature and high pressure, thereby facilitating the deformationthereof into the clearance between the casing and the outer rotor. Itis, thus, difficult to ensure the durability of the sealing mechanismsand achieve the discharging of the brake fluid at high pressure.

SUMMARY OF THE INVENTION

It is therefore an object of this disclosure to provide an improvedstructure of a rotating pump designed to ensure a required degree ofhermetic sealing and capable of discharging fluid at high pressure.

According to one aspect of the invention, there is provided a rotatingpump which may be employed in a brake system for automotive vehicles.The rotating pump comprises: (a) a drive shaft; (b) a rotor assemblymade up of an outer rotor and an inner rotor, the outer rotor havinginner teeth formed on an inner periphery thereof, the inner rotor havingouter teeth formed on an outer periphery thereof and being rotated bythe drive shaft around an axis defined by the drive shaft, the outerteeth meshing with the inner teeth of the outer rotor to define aplurality of cavities; (c) a casing in which the drive shaft isinstalled, the casing including a rotor chamber in which the rotorassembly is mounted to be rotatable with a gap formed between an innerperipheral surface of the casing which faces the outer rotor and anouter peripheral surface of the outer rotor, the casing having an inletport from which fluid is sucked into the rotor assembly and an outletport from which the fluid is discharged with rotation of the rotorassembly; (d) a first and a second recess formed in the inner peripheralsurface of the casing which is exposed to the gap; and (f) a first and asecond sealing member which are disposed in the first and secondrecesses, respectively, to define within the gap a low-pressure regionleading to the inlet port and a high-pressure region leading to theoutlet port. Each of the first and second sealing members is made up ofa seal functioning portion and an elastically pressing portion. The sealfunctioning portion is placed in contact with the outer periphery of theouter rotor and a low-pressure side surface that is a portion of aninner wall surface of a corresponding one of the first and secondrecesses which is closer to the low-pressure region than to thehigh-pressure region to establish a difference in pressure between thelow-pressure region and the high-pressure region. The elasticallypressing portion is located closer to a bottom of a corresponding one ofthe first and second recesses than the seal functioning portion is andworks to press the seal functioning portion against the outer peripheryof the outer rotor. The seal functioning portion includes a resinousmember and a deformation-suppressing member. The resinous member isplaced in contact with the outer periphery of the outer rotor and thelow-pressure side surface of the inner wall surface of a correspondingone of the first and second recesses to establish the difference inpressure between the low-pressure region and the high-pressure region.The deformation-suppressing member is made of material which is morerigid than that of the resinous member and located closer to thelow-pressure region than the resinous member is. A boundary between asurface of the deformation-suppressing member which faces thelow-pressure side surface and a surface of the resinous member whichfaces the low-pressure side surface is located inside a correspondingone of the recesses.

The first and second sealing members are, as described above, installedin the casing to hermetically isolate between the low-pressure regionand the high-pressure region in the gap. Specifically, the sealfunctioning portion of each of the first and second sealing members ispressed by an elastically reactive force, as produced by the elasticallypressing portion, and the high pressure of the fluid in the gap towardthe low-pressure region in the gap, thereby bringing the resinous memberinto constant abutment with the inner wall of a corresponding of thefirst and second recesses in addition to the outer periphery of theouter rotor and an inner wall of the casing to establish a hermetic sealbetween the high-pressure region and the low-pressure region in the gap.

The resinous member is pressed by the high pressure of the fluid, butstopped by the deformation-suppressing member of the seal functioningportion from being deformed into the low-pressure region of the gap,thereby minimizing the risk of breakage of the resinous member to ensurethe stability of sealing the gap. This enables the rotating pump todischarge the fluid at an increased pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinbelow and from the accompanying drawings of thepreferred embodiments of the invention, which, however, should not betaken to limit the invention to the specific embodiments but are for thepurpose of explanation and understanding only.

In the drawings:

FIG. 1 is a circuit diagram which illustrates a brake system equippedwith a rotating pump according to the first embodiment of the invention;

FIG. 2 is a partially sectional view which illustrates an internalstructure of the rotating pump of FIG. 1;

FIG. 3( a) is an enlarged view of a sealing member shown in FIG. 2;

FIG. 3( b) is an illustration which shows a seal functioning portion ofa sealing member, as viewed in an axial direction of a drive shaft ofthe rotating pump of FIG. 2;

FIG. 3( c) is an illustration of the seal functioning portion of FIG. 3(b), as viewed from the center of the rotating pump in a radius directionof the drive shaft;

FIG. 4 is an illustration which shows layout of the sealing member shownin FIG. 2, as viewed from the center of the rotating pump in a radiusdirection of a drive shaft of the rotating pump;

FIG. 5 is an illustration which shows a first modification of a sealingmember, as viewed in an axial direction of a drive shaft of the rotatingpump of FIG. 2;

FIG. 6 is an illustration which shows a second modification of a sealingmember, as viewed in an axial direction of a drive shaft of the rotatingpump of FIG. 2;

FIG. 7 is an illustration which shows a third modification of a sealingmember, as viewed in an axial direction of a drive shaft of the rotatingpump of FIG. 2;

FIG. 8( a) is an illustration which shows a first modification of ajoining structure of a resinous member and a deformation-suppressingmember of a sealing member, as viewed in an axial direction of a driveshaft of the rotating pump of FIG. 2;

FIG. 8( b) is a sectional illustration of the joining structure in FIG.8( a), as viewed from the center of the rotating pump in a radiusdirection of the drive shaft;

FIG. 9( a) is an illustration which shows a second modification of ajoining structure of a resinous member and a deformation-suppressingmember of a sealing member, as viewed in an axial direction of a driveshaft of the rotating pump of FIG. 2;

FIG. 9( b) is a sectional illustration of the joining structure in FIG.9( a), as viewed in a radius direction of the drive shaft;

FIG. 10( a) is an illustration which shows a third modification of ajoining structure of a resinous member and a deformation-suppressingmember of a sealing member, as viewed in an axial direction of a driveshaft of the rotating pump of FIG. 2;

FIG. 10( b) is a sectional illustration of the joining structure in FIG.10( a), as viewed in a radius direction of the drive shaft; and

FIG. 11 is an illustration which shows a fourth modification of ajoining structure of a resinous member and a deformation-suppressingmember of a sealing member, as viewed in an axial direction of a driveshaft of the rotating pump of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments will be described below with reference to the drawingswherein like reference numbers refer to like or equivalent parts inseveral views.

First Embodiment

Referring to FIG. 1, there is shown an automotive brake system equippedwith a rotating pump that is a part of a hydraulic circuit of the brakesystem. The brake system, as referred to herein, is designed as aso-called diagonal split system which includes two brake hydrauliccircuits one of which controls the right front and the left rear wheeland the other of which controls the left front and the right rear wheel,but may be engineered as a front/rear split system.

The brake system is equipped with a brake pedal 1 (i.e., a brakeactuating member) to be depressed by a vehicle occupant or driver forapplying the brakes to the vehicle, a brake booster 12, a mastercylinder 3, wheel cylinders 4 and 5, and a brake pressure controlactuator 6. The master cylinder 3, as will be described later in detail,works to produce a braking hydraulic pressure in response to anoperation of the brake actuating member (i.e., the brake pedal 1).

The brake pedal 1 is connected to the brake booster 2 and the mastercylinder 3. When the driver of the vehicle depresses the brake pedal 1,the brake booster 2 works to boost the pressure applied to the brakepedal 1. Specifically, the brake booster 2 is equipped with a push rodwhich works to push master pistons installed in the master cylinder 3,thereby developing the pressure (which will also be referred to as M/Cpressure below).

To the master cylinder 3, a master reservoir 3 a is connected whichstores therein an excess of the brake fluid in the master cylinder 3.

The M/C pressure is transmitted to the front right wheel cylinder 4 andthe rear left wheel cylinder 5 as wheel cylinder (W/C) pressure. Thebrake pressure control actuator 6 is disposed between the mastercylinder 3 and the wheel cylinders 4 and 5 and works to control the W/Cpressure, as developed in each of the wheel cylinders 4 and 5.

The brake pressure control actuator 6 includes a first hydraulic circuitand a second hydraulic circuit. The first hydraulic circuit is ahydraulic circuit working to control the brake fluid to be applied tothe front right wheel FR (i.e., the wheel cylinder 4) and the left rearwheel RL (i.e., the wheel cylinder 5). The second hydraulic circuit is ahydraulic circuit working to control the brake fluid to be applied tothe left front wheel FL and the right rear wheel RR. The first hydrauliccircuit and the second hydraulic circuit are substantially identical instructure with each other. The following discussion will refer only tothe first hydraulic circuit for the brevity of disclosure.

The brake system (i.e., the first hydraulic circuit) is equipped with amain hydraulic line A (also called a main hydraulic path below)connecting with the master cylinder 3. The main hydraulic line A hasdisposed therein a differential pressure control valve 7 which dividesthe main hydraulic line A into two: a pipe line A1 which is a hydraulicline extending from the master cylinder 3 to the differential pressurecontrol valve 7 and subjected to the M/C pressure and a pipe line A2which is a hydraulic line extending from the differential pressurecontrol valve 7 to the wheel cylinders 4 and 5.

The differential pressure control valve 7 is operable in either of twomodes: an open mode and a pressure-difference mode. In a normal brakingmode where it is required to produce the braking force as a function ofan amount of depression of the brake pedal 11 by the driver, the valveposition of the differential pressure control valve 7 is placed in theopen mode. When the valve position of the differential pressure controlvalve 7 is placed in the pressure-difference mode, the differentialpressure control valve 7 works to control the flow of the braking fluidto elevate and hold the W/C pressures above the M/C pressure by apressure difference, as developed by the differential pressure controlvalve 7.

The pipe line A2 includes two branch lines: one being equipped with apressure-increasing valve 8 a which increases the pressure of the brakefluid supplied to the wheel cylinder 4, and one being equipped with apressure-increasing valve 8 b which increases the pressure of the brakefluid supplied to the wheel cylinder 5.

Each of the pressure-increasing valves 8 a and 8 b is implemented by atwo-position valve which is opened or closed by a brake electroniccontrol unit (ECU), not shown, to control increasing of the brakinghydraulic pressure (i.e., the pressure of the brake fluid applied to thewheel cylinder 4 or 5). Specifically, when the pressure-increasing valve8 a is opened, the pressure of the brake fluid, as created by the M/Cpressure, is transmitted to the wheel cylinder 4. In a normal brakingmode where brake fluid pressure control, such as an anti-lock brakecontrol, is not executed, the pressure-increasing valve 8 a is opened.The same is true for the pressure-increasing valve 8 b.

The brake pressure control actuator 6 also includes a hydraulic line Bwhich extends as a pressure-reducing path between a pressure controlreservoir 9 and a junction of the pressure-increasing valve 8 a and thewheel cylinder 4 and between the pressure control reservoir 9 and ajunction of the pressure-increasing valve 8 b and the wheel cylinder 5.The brake fluid is drained to the pressure control reservoir 9 throughthe hydraulic line B to control the W/C pressure exerted on the wheelcylinders 4 and 5 to prevent the wheels of the vehicle from locking.

The hydraulic line B is equipped with pressure-reducing valves 10 a and10 b which are each implemented by a two-position solenoid valve. Thepressure-reducing valves 10 a and 10 b are opened or closed by the brakeECU to control decreasing of the braking hydraulic pressure (i.e., thepressure of the brake fluid applied to the wheel cylinder 4 or 5). Inthe normal braking mode where the brake fluid pressure control is notexecuted, the pressure-reducing valves 10 a and 10 b are kept closed.When it is required to drain the brake fluid to the pressure controlreservoir 9, the pressure-reducing valves 10 a and 10 b are opened.

The brake pressure control actuator 6 also includes a hydraulic line Cwhich extends between the pressure control reservoir 9 and the hydraulicline A. The hydraulic line C is equipped with a pump 11 which isdisposed between a junction of the differential pressure control valve 7and the pressure-increasing valves 8 a and 8 b and driven by an electricmotor 12. The hydraulic line C also has check valves 11 a and 11 bmounted across the pump 11.

The hydraulic line C is also equipped with an accumulator 13 disposeddownstream of the pump 11 to alleviate pulsation of the brake fluiddischarged from the pump 11. The brake pressure control actuator 6 alsoincludes a hydraulic line D which extends as a sub-hydraulic linebetween the pressure control reservoir 9 and the master cylinder 3. Thepump 11 works to suck the brake fluid from the hydraulic line A1 throughthe hydraulic line D and the pressure control reservoir 9 and output itto the hydraulic line A2 to elevate the W/C pressures.

The second hydraulic circuit, as already described, has the samestructure as described above as that of the first hydraulic circuit. Thecontrol valves 7, 8 a, 8 b, 10 a, and 10 b, the rotating pump 11, thepressure control reservoir 9, and the motor 12 are installed in ahousing which is drilled to define the above described hydraulic linesand constitute the brake pressure control actuator 6. The brake pressurecontrol actuator 6 is, as described above, disposed between the mastercylinder 3 and the wheel cylinders 4 and 4, thereby making the brakesystem, as illustrated in FIG. 1.

The brake system works to execute brake fluid pressure control taskssuch as the ABS control, the brake assist control, the adaptive cruisecontrol, and the regenerative braking control and drive the rotatingpump 11 to suck or discharge the brake fluid. In recent years, it hasbeen required to develop the high W/C pressure quickly; for example, inthe brake assist control mode or the adaptive cruise control mode whereit is necessary to actuate the rotating pump 11 to create a highpressure of brake fluid. The discharge pressure of the rotating pump 11is, thus, required to be increased.

In order to meet the above requirement, the rotating pump 11 of thisembodiment is engineered in the following way. The structure of therotating pump 11 will be described in detail with reference to FIGS. 2,3, and 4.

The rotating pump 11 is installed in a rotor chamber 50 a of a casing50. Specifically, within the rotor chamber 50 a, an outer rotor 51 andan inner rotor 52 are arranged with center axes X and Y thereof beingeccentric from each other. A combination of the outer rotor 51 and theinner rotor 52 works as a rotor assembly in the rotating pump 11.

The outer rotor 51 has inner teeth 51 a formed on an inner peripherythereof. The inner rotor 52 has outer teeth 52 a formed on an outerperiphery thereof. The inner teeth 51 a of the outer rotor 51 mesh withthe outer teeth 52 a of the inner rotor 52 so as to create a pluralityof gaps or enclosed cavities 53 therebetween. More specifically,surfaces of the inner teeth 51 a and the outer teeth 52 a are placed incontact with each other to define the cavities 53. The outer rotor 51and the inner rotor 52 are rotated by a drive shaft 54 arranged in thecenter of the inner rotor 52, so that the cavities 53 are changed involume thereof with rotation of the drive shaft 54, thereby sucking ordischarging the brake fluid.

The thus constructed rotating pump 11 is a multi-tooth trochoid pumpwith no crescent in which the inner teeth 51 a of the outer rotor 51 andthe outer teeth 52 a of the inner rotor 52 mesh with each other todefine the cavities 53. The meshing surfaces of the outer teeth 52 acontact at a plurality of points with those of the inner teeth 51 a totransmit torque from the inner rotor 52 to the outer rotor 51.

The casing 50 includes a center plate 50 b and side plates 50 c and 50d, as illustrated in FIG. 4. The center plate 50 b embraces the outerperipheries of the rotors 51 and 52. The side plates 50 c and 50 dsandwich axially-opposed end surfaces of the rotors 51 and 52 and thecenter plate 50 b. The center plate 50 b and the side plates 50 c and 50d form a space which defines the rotor chamber 50 a. The side plates 50c and 50 d have center holes (not shown) in which the drive shaft 54 isfit. The outer rotor 51 and the inner rotor 52 are disposed to berotatable within the rotor chamber 50 a. In other words, a rotatableassembly of the outer rotor 51 and the inner rotor 52 is arrangedrotatably in the rotor chamber 50 a of the casing 50, so that the outerrotor 51 may rotate about the axis X, and the inner rotor 52 may rotateabout the axis Y. The axis Y is an axis of rotation of the inner rotor52 defined by the drive shaft 54 (i.e., a longitudinal center line ofthe drive shaft 54).

If a line traversing perpendicular to the axes X and Y of the outerrotor 51 and the inner rotor 52 is, as illustrated in FIG. 2, defined asthe center line Z of the rotating pump 11, the side plate 50 c has aninlet port 60 and an outlet port 61 which are located on the left andright sides of the center line Z and communicate with the rotor chamber50 a. The inlet port 60 communicates with some of the cavities 53through which the brake fluid is sucked into the pump 11. The outletport 61 which communicates with some of the cavities 53 through whichthe brake fluid is discharged from the pump 11.

The enclosed cavity 53 a that is one of the cavities 53 which has thegreatest volume does not communicate with the inlet port 60 or with theoutlet port 61. The cavity 53 a works to develop a difference betweenthe suction pressure in the inlet port 60 and the discharge pressure inthe outlet port 61. One of the side plates 50 c and 50 d has a firstflow path and a second flow path formed therein. The first flow pathcommunicates between an annular gap S on the outer circumference of theouter rotor 51, that is, a clearance between the outer periphery of theouter rotor 51 and the inner wall of the casing 50 (i.e., the inner wallof the rotor chamber 50 a) and the inlet port 60, while the second flowpath communicates between the gap S and the outlet port 61. This createsa low-pressure region, as defined by a portion of the gap S, as will bedescribed later in detail, communicating with the inlet port 60, and ahigh-pressure region, as defined by a portion of the gap S communicatingwith the outlet port 61. In practice, the gap S is, as can be seen inFIG. 2, blocked on the side of the outlet port 61.

The center plate 50 b of the casing 50, as clearly illustrated in FIG.2, has recesses 50 e and 50 f formed in the inner wall thereof. Therecesses 50 e and 50 f will also be referred to as a first and a secondrecess below. Each of the recesses 50 e and 50 f is located at a givenangle away from the center line Z toward the inlet port 60 around theaxis Y (i.e., the rotating center) of the outer rotor 51. In otherwords, each of the recesses 50 e and 50 f lies on a circle, as definedabout the axis Y, and is separate from the center line Z by the givenangle. Sealing members 80 and 90 are mounted in the recesses 50 e and 50f to stop the brake fluid from flowing within the gap S on the outercircumference of the outer rotor 51. In other words, the sealing members80 and 90 are separate from each other in a circumferential direction ofthe outer rotor 51 through a portion of the gap S which faces andcommunicates with the inlet port 60. The sealing members 80 and 90 willalso be referred to as a first and a second sealing member below.

The sealing members 80 and 90 work to hermetically isolate ahigh-pressure portion (i.e., the high-pressure region) and alow-pressure portion (i.e., the low-pressure region) of the gap S,thereby avoiding the flow of the brake fluid from the high-pressureregion to the low-pressure region. In other words, the sealing members80 and 90 serve to keep a portion of the gap S which communicates withthe inlet port 60 at the suction pressure and a portion of the gap Swhich communicates with the outlet port 61 at the discharge pressure,thereby developing a balance in pressure between outside and inside theouter rotor 51. This prevents the outer rotor 51 from being pressed bythe pressure of the brake fluid locally against the inner rotor 52 andthe casing 50, thereby minimizing irregular wear of the teeth 51 a and52 a and the outer periphery of the outer rotor 51.

FIGS. 3( a) to 3(c) illustrate the structure of the sealing member 80 indetail. The sealing member 90 is identical in structure with the sealingmember 80. The following discussion will, thus, refer only to thesealing member 80 for the sake of simplicity of explanation.

The sealing member 80 is, as can be seen in FIGS. 3( a) to 3(c), made upof two parts: a seal functioning portion 81 and an elastically pressingportion 82.

The seal functioning portion 81 is pressed against the circumferentialsurface of the outer rotor 51 and the side plates 50 c and 50 d toestablish a hermetical seal in the gap S, that is, to seal between thehigh-pressure region and the low-pressure region. The seal functioningportion 81 is made up of a resinous block 81 a and adeformation-suppressing block 8 b. The seal functioning portion 81 issubstantially of a pentagonal prism shape. The main part of the sealfunctioning portion 81 is made of the resinous block 81 a, while theother part of the seal functioning portion 81 is made of thedeformation-suppressing block 81 b to define a surface of the sealfunctioning portion 81 exposed to the low-pressure region of the gap S.In other words, the deformation-suppressing block 81 b is arranged so asto define a portion of the seal functioning portion 81 which is exposedto the low-pressure region of the gap S, while the resinous block 81 ais shaped or located so as not to be exposed to the low-pressure regionof the gap S.

The resinous block 81 a is made of a soft resin such as Teflon (TradeMark). The resinous block 81 a is shaped to have outer surfacescontacting the outer circumference of the outer rotor 51 (see FIG. 3(a)), the side plates 50 c and 50 d (see FIG. 4), and the inner wallsurface of the recess 50 e, i.e., a portion (which will also be referredto as a low-pressure side surface below) of the inner wall of the recess50 e which is closer to the low-pressure side than to the high-pressureside in the gap S. The circumference (i.e., the outer peripheralsurface) and the side surfaces of the deformation-suppressing block 81 bare substantially entirely enclosed or surrounded by the surfaces of therecess 50 e, the resinous block 81 a, the side plates 50 c and 50 d, andthe outer rotor 51, thereby hermetically isolating between thehigh-pressure region and the low-pressure region in the gap S to developa desired difference in pressure between the high-pressure region andthe low-pressure region. The resinous block 81 a is shaped to have adimension (i.e., length L₁ in FIG. 4) in the same direction as the axialdirection of the outer rotor 51 (i.e., a direction parallel to the axisof rotation of the inner rotor 52) which is set greater than thethickness of the rotor chamber 50 a in the axial direction of the outerrotor 51 (i.e., an interval between the side surfaces of the side plates50 c and 50 d in a thickness-wise direction thereof). This causes theresinous block 81 a, as indicated by a broken line in FIG. 4, to beelastically squeezed or deformed, so that the length (i.e., thedimension in the vertical direction in FIG. 4) of the resinous block 81a is decreased, thereby enhancing the ability to seal the gap S.

The resinous block 81 a is also shaped to have the flat surface 81 aa,as illustrated in FIGS. 3( a) and 3(b), which is diagonally opposed tothe surface thereof with which the deformation-suppressing block 81 b isplaced in contact. The surface 81 aa may be formed to extendsubstantially parallel to the surface the deformation-suppressing block81 b contacts. The elastically pressing portion 82 of the sealing member80 is urged into abutment with the surface 81 aa of the resinous block81 a.

The deformation-suppressing block 81 b is made from material such asresin or metal which is more rigid than the resinous block 81 a andworks as a stopper to stop the resinous block 81 a from elasticallydeforming toward the gap S. Specifically, the deformation-suppressingblock 81 b is located to be exposed to the low-pressure region of thegap S. In other words, the deformation-suppressing block 81 b lies at aportion of the seal functioning portion 81 which is exposed to thelow-pressure region of the gap S, so that the resinous block 81 a is notexposed to the low-pressure region.

The deformation-suppressing block 81 b is formed in the shape of atriangular prism made of two triangular bases and three side faces wherethe triangular bases are the end surfaces of the deformation-suppressingblock 81 b which face the side plates 50 c and 50 d, and the side facesare the side surfaces of the deformation-suppressing block 81 b whichextend in the axial direction of the outer rotor 51. Thedeformation-suppressing block 81 b is dimensionally formed so that oneof the side surfaces thereof partially faces or is partially exposed tothe gap S, and a boundary 100, as illustrated in FIG. 3( a), between theone of the side surfaces and the surface of the resinous block 81 a liesinside the recess 50 e. The deformation-suppressing block 81 b is alsoshaped to have a dimension (i.e., length L₂) in the same direction asthe axial direction of the outer rotor 51 (i.e., a direction parallel tothe axis of rotation of the inner rotor 52) which is, as can be seenfrom FIG. 4, set smaller than the thickness of the rotor chamber 50 a inthe axial direction of the outer rotor 51 (i.e., the minimum intervalbetween the side surfaces of the side plates 50 c and 50 d ).

The resinous block 81 a and the deformation-suppressing block 81 b maybe mechanically joined together or separate from each other. In thisembodiment, they are joined together. Specifically, the resinous block81 a, as illustrated in FIG. 3( c), has a wedge-shaped recess 81 abformed in the surface thereof which diagonally faces the outer rotor 51.The wedge-shaped recess 81 ab is shaped to have a depth, as can be seenfrom FIG. 3( b), substantially extending from the side of thelow-pressure region to the side of the high-pressure region of the gapS. In other words, the wedge-shaped recess 81 ab is recessed from theside of the low-pressure region to the side of the high-pressure regionof the gap S. The deformation-suppressing block 81 b is shaped to have awedge-shaped protrusion 81 ba formed on the surface thereof which facesthe resinous block 81 a. The wedge-shaped protrusion 81 ba projectstoward the high-pressure region of the gap S. The wedge-shapedprotrusion 81 ba is fit in the wedge-shaped recess 81 ab to establishthe joint of the resinous block 81 a and the deformation-suppressingblock 81 b.

The seal functioning portion 81 is made up of the resinous block 81 aand the deformation-suppressing block 81 b in the above way.

The elastically pressing portion 82 is made of an elastically deformablematerial such as rubber and located deeper than the seal functioningportion 81 within the recess 50 e, in other words, closer to the bottomof the recess 50 e than the seal functioning portion 81 is. Theelastically pressing portion 82 is elastically deformed within therecess 50 e, thereby creating a reactive force which presses theresinous block 81 a of the seal functioning portion 81 against the outerwall surface of the outer rotor 51 and the inner wall surface of therecess 50 e. In other words, the elastically pressing portion 82 iselastically deformed between the inner wall surface of the recess 50 eand the surface 81 aa of the resinous block 81 a of the seal functioningportion 81, thereby pressing the surface 81 a a to urge the resinousblock 81 a against the inner wall of the recess 50 e and the outercircumference of the outer rotor 51. This establishes a liquid-tightseal in the gap S, that is, hermetically blocks the gap S to isolatebetween the high-pressure region and the low-pressure region.

The operations of the brake system and the rotating pump 11 will bedescribed below. For instance, when one of the above described brakefluid pressure control tasks is initiated, the control valves 7 and 30to 33 are actuated according to the control mode, as specified by theone of the brake fluid pressure control tasks. Simultaneously, the motor12 is actuated to suck and then discharge the brake fluid through thepump 11.

Specifically, when the motor 12 is actuated, the inner rotor 51 of thepump 11 is rotated by the drive shaft 54, thereby rotating the outerrotor 51 in the same direction as the inner rotor 51 through the meshingof the inner teeth 51 a with the outer teeth 52 a. The volumes of thecavities 53 are changed sequentially every rotation of the outer rotor51 and the inner rotor 52, thereby sucking the brake fluid from theinlet port 60 and then discharge it from the outlet port 61 to thehydraulic line A2 to elevate the W/C pressure.

In the above way, the rotating pump 11 performs a normal pumpingoperation in which the rotors 51 and 52 are rotated to suck the brakefluid from the inlet port 60 and then discharge it from the outlet port61. During the normal pumping operation, a portion of the gap S on theouter circumference of the outer rotor 51 communicating with the inletport 60 is kept at the suction pressure, while a portion of the gap Scommunicating with the outlet port 61 is kept at the discharge pressure.This creates, as described above, the low-pressure region and thehigh-pressure region in the gap S.

The sealing members 80 and 90 are, as described above, installed in thecenter plate 50 b of the casing 50 to hermetically isolate between thelow-pressure region and the high-pressure region in the gap S.Specifically, the seal functioning portion 81 of each of the sealingmembers 80 and 90 is pressed by the elastically reactive force, asproduced by the elastically pressing portion 82, and the high pressureof the brake fluid in the gap S toward the low-pressure region in thegap S, thereby bringing the resinous block 81 a into constant abutmentwith the inner wall of the recess 50 e in addition to the outercircumferential surface of the outer rotor 51 and the surfaces of theside plates 50 c and 50 d to establish the hermetic seal between thehigh-pressure region and the low-pressure region in the gap S.

The resinous block 81 a is pressed by the high pressure of the brakefluid, but stopped by the deformation-suppressing block 81 b of the sealfunctioning portion 81 from being deformed into the low-pressure regionof the gap S, thereby minimizing the risk of breakage of the resinousblock 81 a to ensure the stability of sealing the gap S. This enablesthe rotating pump 11 to discharge the brake fluid at an increasedpressure.

Other Embodiments

While the present invention has been disclosed in terms of the preferredembodiment in order to facilitate better understanding thereof, itshould be appreciated that the invention can be embodied in various wayswithout departing from the principle of the invention.

For instance, the seal functioning portion 81 of each of the sealingmembers 80 and 90 may be engineered to have the resinous block 81 a andthe deformation-suppressing block 81 b which are mechanically separatefrom each other. In this case, it is also advisable that at least theboundary 100 between one of the side surfaces of thedeformation-suppressing block 81 b which is exposed to the low-pressureregion of the gap S and the surface of the resinous block 81 a whichfaces in the same direction as the one of the side surfaces of thedeformation-suppressing block 81 b be located fully within acorresponding one of the recesses 50 e and 50 f.

The deformation-suppressing block 81 b may be, as illustrated in FIG. 6,formed in the shape of a circular cylinder made of two circular basesand a side face substantially perpendicular to the circular bases wherethe circular bases are the end surfaces of the deformation-suppressingblock 81 b which face the side plates 50 c and 50 d, and the side faceis the side surface of the deformation-suppressing block 81 b whichextends in the axial direction of the outer rotor 51. In this case, whenthe rotating pump 11 is at rest in operation, the resinous block 81 a islocated far away from the deformation-suppressing block 81 b on aportion of the inner surface of, for example, the recess 50 e which iscloser to the low-pressure region than to the high-pressure region ofthe gap S, thus facilitating the ease of elastic deformation of theresinous block 81 a into the gap S. This problem, however, may bealleviated by making the deformation-suppressing block 81 b to have aradius greater than the thickness of the gap S (i.e., the dimension ofthe gap S in the radius direction of the outer rotor 50). In otherwords, it is advisable that the deformation-suppressing block 81 b beshaped so that a boundary between the resinous block 81 a and thedeformation-suppressing block 81 b on a portion of the inner wall of,for example, the recess 50 e which is closer to the low-pressure regionthan to the high-pressure region fully lies, like in the firstembodiment, inside the recess 50 e when the resinous block 81 a isdeformed most greatly. The same applies to the case where thedeformation-suppressing block 81 b is of a shape other than thetriangular prism or the circular cylinder. Specifically, the deformationof the resinous block 81 a into the gap S is avoided by making thedeformation-suppressing block 81 b to have a dimension greater than thatof the gap S in the radius direction of the drive shaft 54 (i.e., theouter rotor 51) so that the deformation-suppressing block 81 b is atleast partially placed in contact with the inner wall of the recess 50e.

The deformation-suppressing block 81 b may alternatively be, asillustrated in FIG. 7, formed in the shape of a quadrangular prism madeof two square or rectangular bases and four side faces substantiallyperpendicular to the rectangular bases where the rectangular bases arethe end surfaces of the deformation-suppressing block 81 b which facethe side plates 50 c and 50 d, and the side faces are the side surfacesof the deformation-suppressing block 81 b which extend in the axialdirection of the outer rotor 51.

The jointing of the resinous block 81 a and the deformation-suppressingblock 81 b of the seal functioning portion 81 may be changed from theone, as illustrated in FIGS. 3( b) and 3(c). The following discussionwill refer to the case where the deformation-suppressing block 81 b is,as illustrated in FIG. 7, of a quadrangular prism shape, but however,the same joining structure as described below may be used in the casewhere the deformation-suppressing block 81 b is substantially of atriangular prism shape, as illustrated in FIG. 5, or a circularcylindrical shape, as illustrated in FIG. 6.

Specifically, the resinous block 81 a, as illustrated in FIGS. 8( a) and8(b), has formed on the surface thereof a protrusion 81 ac whichprojects toward the low-pressure region of the gap S. Thedeformation-suppressing block 81 b is shaped to have a recess 81 bbwhich is shaped to have a depth, as can be seen from FIG. 8( b),substantially extending from the side of the high-pressure region to theside of the low-pressure region of the gap S. In other words, the recess81 bb is recessed from the side of the high-pressure region to the sideof the low-pressure region of the gap S. The protrusion 81 ac is fit inthe recess 81 bb to establish the mechanical joint between the resinousblock 81 a and the deformation-suppressing block 81 b.

The jointing of the resinous block 81 a and the deformation-suppressingblock 81 b of the seal functioning portion 81 may alternatively beestablished in the way, as illustrated in FIGS. 9( a) and 9(b).Specifically, the deformation-suppressing block 81 b has a protrusion 81ba formed on two of the side surfaces thereof which face the resinousblock 81 a (i.e., the side surfaces of the deformation-suppressing block81 b which contact the resinous block 81 a ) The protrusion 81 ba is ofa U-shaped in traverse cross section and extends from the corner of thedeformation-suppressing block 81 b which faces the outer rotor 51 to thecorner of the deformation-suppressing block 81 b which faces a portionof the inner wall of the recess 50 e which is closer to the low-pressureregion of the gap S. The resinous block 81 a has formed therein a recessor groove 81 ab which extends from the surface thereof which faces theouter rotor 51 and to the surface thereof which faces the portion of theinner wall of the recess 50 e which is closer to the low-pressure regionof the gap S. In other words, the groove 81 ab is formed in the surfaceof the resinous block 81 a which faces the deformation-suppressing block81 b. The groove 81 ab is of a U-shaped in traverse cross section. Theprotrusion 81 ba of the deformation-suppressing block 81 b is fit in thegroove 81 ab of the resinous block 81 a to establish the mechanicaljoining of the resinous block 81 a and the deformation-suppressing block81 b.

The jointing of the resinous block 81 a and the deformation-suppressingblock 81 b of the seal functioning portion 81 may alternatively beestablished in the way, as illustrated in FIGS. 10( a) and 10(b).Specifically, the deformation-suppressing block 81 b has asemi-cylindrical protrusion 81 bc formed on one of the corners thereofwhich face the resinous block 81 a. In other words, the protrusion 81 bcis formed on the surface of the deformation-suppressing block 81 b whichcontacts the resinous block 81 a. The resinous block 81 a has asemi-cylindrical recess or groove 81 ad formed in the inner cornerthereof which faces the deformation-suppressing block 81 b. In otherwords, the groove 81 ad is formed in the surface of the resinous block81 a which faces the deformation-suppressing block 81 b. The protrusion81 bc of the deformation-suppressing block 81 b is fit in the groove 81ad of the resinous block 81 a to establish the mechanical joining of theresinous block 81 a and the deformation-suppressing block 81 b.

The jointing of the resinous block 81 a and the deformation-suppressingblock 81 b of the seal functioning portion 81 may alternatively beestablished, as illustrated in FIG. 11, by embedding at least a portionof the deformation-suppressing block 81 b in the resinous block 81 a. Inother words, the side surface of the resinous block 81 a which faces thedeformation-suppressing block 81 b is partially wrapped around the sidesurfaces of the deformation-suppressing block 81 b to establish themechanical joint between the resinous block 81 a and thedeformation-suppressing block 81 b.

What is claimed is:
 1. A rotating pump comprising: a drive shaft; arotor assembly made up of an outer rotor and an inner rotor, the outerrotor having inner teeth formed on an inner periphery thereof, the innerrotor having outer teeth formed on an outer periphery thereof and beingrotated by the drive shaft around an axis defined by the drive shaft,the outer teeth meshing with the inner teeth of the outer rotor todefine a plurality of cavities; a casing in which the drive shaft isinstalled, the casing including a rotor chamber in which the rotorassembly is mounted to be rotatable with a gap formed between an innerperipheral surface of the casing which faces the outer rotor and anouter peripheral surface of the outer rotor, the casing having an inletport from which fluid is sucked into the rotor assembly and an outletport from which the fluid is discharged with rotation of the rotorassembly; a first and a second recess formed in the inner peripheralsurface of the casing which is exposed to the gap; and a first and asecond sealing member which are disposed in the first and secondrecesses, respectively, to define within the gap a low-pressure regionleading to the inlet port and a high-pressure region leading to theoutlet port, each of the first and second sealing members being made upof a seal functioning portion and an elastically pressing portion, theseal functioning portion being placed in contact with the outerperiphery of the outer rotor and a low-pressure side surface that is aportion of an inner wall surface of a corresponding one of the first andsecond recesses which is closer to the low-pressure region than to thehigh-pressure region to establish a difference in pressure between thelow-pressure region and the high-pressure region, the elasticallypressing portion being located closer to a bottom of a corresponding oneof the first and second recesses than the seal functioning portion isand working to press the seal functioning portion against the outerperiphery of the outer rotor, the seal functioning portion including aresinous member and a deformation-suppressing member, the resinousmember being placed in contact with the outer periphery of the outerrotor and the low-pressure side surface of the inner wall surface of acorresponding one of the first and second recesses to establish thedifference in pressure between the low-pressure region and thehigh-pressure region, the deformation-suppressing member being made ofmaterial which is more rigid than that of the resinous member andlocated closer to the low-pressure region than the resinous member is, aboundary between a surface of the deformation-suppressing member whichfaces the low-pressure side surface and a surface of the resinous memberwhich faces the low-pressure side surface being located inside acorresponding one of the recesses.
 2. A rotating pump as set forth inclaim 1, wherein the deformation-suppressing member of the sealfunctioning portion has a dimension which is smaller than that of therotor chamber in a direction parallel to an axis of rotation of theouter rotor.
 3. A rotating pump as set forth in claim 1, wherein theresinous member of the seal functioning portion has a dimension which isgreater than that of the rotor chamber in a direction parallel to anaxis of rotation of the inner rotor, and wherein the resinous member iselastically deformed in the direction parallel to the axis of rotationof the outer rotor and disposed in the casing.